A Hydrodynamic Particulate Approach to Pit Membrane Pore Size Distribution

This paper deals with a satisfactory means for investigating the pore size distribution within the border pit membranes of conifers. It deals with the use of size control particulate material in conjunction with a well controlled liquid flow system. Kiln-dried spruce heartwood was used for the major development of this test experiment. The lengths were chosen so that they would be slightly longer than the maximum tracheid length for the species, thus insuring that in every case flow must occur through at least one pit membrane, but seldom more than one. Apparatus included supply tanks, a cell device for encasing a wood sample during flow, a system for accurate measurement, a regulating pressure gage, a filter system, and two ultrasonic transducers to aid in the deaeration of the liquid. Experimental results of this study have led to the following conclusions: 1) In a wood-water system, a constant flow rate of equal magnitude through the two longitudinal directions of the specimen is a satisfactory indication of the absence of air in the system and can be obtained by using either heartwood or sapwood. 2) A particulate suspension properly introduced into a wood-water system will result in reduced flow until a new equilibrium rate is reached, which can then be maintained regardless of whether the permeating fluid is the suspension or pure water.

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